Vehicles include a drivetrain that may include a charge sustaining or charge depleting (CS/CD) hybrid propulsion configuration (which may or may not be designed to accept battery charge power from an external electric energy source, i.e., a plug in hybrid) or a range extended full electric propulsion configuration to propel the vehicle. In either configuration, the drivetrain includes an internal combustion engine, a first electric motor, a second electric motor and a transmission. The range extended full electric configuration, used in an extended range electric vehicle (EREV), must be capable of propelling the vehicle on battery power alone until the battery charge is depleted. At that time it transitions to an operating strategy similar to a conventional hybrid in which the engine is operated during some driving conditions to provide drive power and maintain battery state-of-charge. The CS/CD hybrid configuration generally requires the engine to operate in order to provide full vehicle power, and is designed to be capable of operating as an electric vehicle only at lower powers. Generally, the first electric motor includes an electric motor/generator, and may be actuated from torque from the internal combustion engine to charge a battery. In a hybrid propulsion configuration, vehicle propulsion may come from any of the internal combustion engine, the first electric motor, the second electric motor, or any combination thereof. Hybrid propulsion configurations generally require a larger internal combustion engine, and utilize smaller batteries than vehicles utilizing the full electric propulsion configuration. For example, a passenger car vehicle utilizing the full electric propulsion configuration may include a battery having a power output of greater than 100 KW, whereas vehicles utilizing the hybrid propulsion configuration may only require a battery having a power output of between 30 and 40 KW.
The different operating strategies between the differing propulsion systems lead to substantially different usage of the electric motors. For example, the electric motors of the full electric propulsion configuration tend to operate at higher speeds and higher powers during operation as an electric vehicle, whereas electric motors of the hybrid propulsion configuration tend to operate at lower speeds and lower powers. Additionally, the second electric motor in a full electric propulsion configuration typically requires a high torque capability to provide adequate launch and reverse gradeability performance. The high torque required from the second electric motor tends to reduce the power and efficiency of the second electric motor at high speeds. Accordingly, the full electric propulsion configuration and the hybrid propulsion configuration generally employ different transmission powerflows, and utilize different electric motors. The electric motors may vary in the number of winding turns and/or the winding connection configuration, in order to provide the required performance characteristics for the specific propulsion configuration utilized.